Oh I get it, so the rank is for the status or quality or genre of food ^^;;;

There is no "C rank". ^^;;
Actually $20-30 per entree is considered A rank in Japan...B-rank is usually less than $10. But then the rank is not strictly classified according the the price, but also the genre and quality of the food. Sometimes French can be B-rank if the taste is rough. But some cheap French ($40 per course) is A-rank if the standard is high. Though B-rank gourmet usually refer to stuff like curry, omelette rice, deep-fried pork steak etc...the classification is very vague actually.

Then how cheap is C Rank? (is there such grade?) US rank use $, $$, $$$ and $$$$. So like the French restaurants I went to are $$ range (US $20-30 entree), can't afford anything beyond that ^^;;

Not shake, just noisy lor. Oh I found it from a "B-rank"(expensive high-class French is called "A-rank" ^^;;) gourmet page.

How interesting ^^:; does the whole place shake when a train passed by? How do you find such place?